I have a '68 442 with the original 400. My father had it rebuilt years ago. He kept the original heads/intake but there is some sort of cam upgrade. Unfortunately I never found out what specs he rebuilt it to.

I have a new 670 cfm Holley on it now. It really likes the most aggressive pump cam (the brown one) to get great throttle response. But with that Holley recommends upgrading to a 50cc pump and .037 nozzle.

Should I have just bought a 770 cfm or is there hope left for me with this one.

 

Also Right now I have the brown cam with the 30 cc pump and a 35 nozzle. It runs great but the throttle Has the potential stick wide open. I believe thats one of the reasons they recommend the 50 cc pump. But when I change to the 50 cc it becomes "sluggish" on acceleration. There is definitely a change.

And I was wrong. Holley recommends the 50 cc when using a 37 nozzle not vice versa. So I dont have to use the 37.

 

Thanks for all yur input!

 

Sorry man, I spend most of my time in the big block section. When you change the nozzle-cam you are changing the amount of fuel you let in. Either way, the 670 carburetor is still only going to flow 670 cfm. You need to figure out what your engine needs...there is a great calculator on Wallace Racing: http://www.wallaceracing.com/intakecfm.php